93 research outputs found
Analysis of space-resolved X-ray spectra from laser plasmas
High dynamic range, space-resolved X-ray spectra, obtained
using a TlAP crystal and a cooled CCD camera as a detector,
were used to investigate the electron density and temperature
profiles of an aluminum laser plasma with micrometer resolution.
The electron density profile retrieved from the measurements
is compared with numerical predictions from the two hydrodynamics
codes MEDUSA (1D) and POLLUX (2D). It is shown that 2D density
profiles can be successfully reproduced by 1D simulations using
a spherical geometry with an ad hoc initial radius, leading
to similar electron temperature profiles
A study of laser plasmas as X-ray sources in the 1-10 keV spectral region
An experimental investigation on X-ray emission from laser-produced plasmas is presented and the properties of such an emission of interest for application purposes are examined. Plasmas were generated by focusing 1 μm, 3 ns Nd laser pulses onto Al and Cu targets at an intensity of 1013 W/cm2. The temporal evolution of the emission and its spectral features were investigated by using an X-ray streak-camera and an X-ray photodiode. In the case of Cu targets, the analysis of the emission showed two spectral components. The main component was centered at ≈ 1.2 keV and a minor component, whose intensity was measured to be 10-3 of the previous component, was observed at ≈7 keV. The X-ray conversion efficiency, in the investigated spectral region, was measured to be 1% for Cu targets and 0.3% for Al targets
Multi-GeV Electron Spectrometer
The advance in laser plasma acceleration techniques pushes the regime of the
resulting accelerated particles to higher energies and intensities. In
particular the upcoming experiments with the FLAME laser at LNF will enter the
GeV regime with almost 1pC of electrons. From the current status of
understanding of the acceleration mechanism, relatively large angular and
energy spreads are expected. There is therefore the need to develop a device
capable to measure the energy of electrons over three orders of magnitude (few
MeV to few GeV) under still unknown angular divergences. Within the PlasmonX
experiment at LNF a spectrometer is being constructed to perform these
measurements. It is made of an electro-magnet and a screen made of
scintillating fibers for the measurement of the trajectories of the particles.
The large range of operation, the huge number of particles and the need to
focus the divergence present unprecedented challenges in the design and
construction of such a device. We will present the design considerations for
this spectrometer and the first results from a prototype.Comment: 7 pages, 6 figures, submitted to NIM
Measurements of thermal transport and absorption in plasmas produced by picosecond laser pulses
High brightness laser–plasma X-ray source at IFAM: Characterization and applications
A high brightness laser-plasma X-ray source has
been set-up and is presently available at IFAM. A wide
range of diagnostics has been set up to monitor the properties
of the X-ray radiation and to control the main parameters
including photon energy, flux intensity, and pulse duration.
A beam extractor enables access to the X-ray radiation
at atmospheric pressure. A simple, easy-to-use projection
microscope has been built which is capable of single-shot
micron resolution imaging with digital acquisition. Preliminary
biomedical experiments show that the X-ray doses available
on a single laser shot exposure of our source fully meet
the conditions required for an important class of biological
experiments based on X-ray induced DNA damage providing
an ideal alternative to the long time exposures needed
with X-ray tubes
Nonlocal effects in the self-consistent nonlinear 3D propagation of an ultrastrong, femtosecond laser pulse in plasmas
A theoretical investigation of the interaction of an ultra-strong and ultra-short laser pulse with unmagnetized plasma is carried out and applied to the specifications of the Ti:Sa Frascati Laser for Acceleration and Multidisciplinary Experiments (FLAME). The analysis is based on the Lorentz-Maxwell fluid model in the fully relativistic regime taking the pancake approximation. The mathematical model yields Zakharov-like equations, which gives a satisfactory description of a wide range of laser-plasma acceleration configurations. It is shown that the pancake structure is unstable in two dimensions (2D) but the collapse occurs over a distance much longer than the typical active plasma length
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